Apart from a few games, Quicken is the last piece of Windows software that I just haven't been able to replace since switching to Mac OS X. The Mac version of Quicken is pretty much universally hated and is, from all accounts, a buggy piece of crap, and I have no desire to boot up a Windows VM in order to run the Windows version.
I tried a few other OS X finance apps and wasn't happy with most of them. MoneyWell was nice enough that I actually ended up buying a copy, but after a few weeks of use I discovered that it's just not as convenient as Quicken was (it also suffers from a few annoying bugs).
In terms of web apps, Mint is okay, but pretty limited, occasionally glitchy, and spammy. Buxfer is nicer, but often frustratingly slow, and still not as advanced (or as automated) as I'd like.
Somehow, while searching high and low for a Quicken replacement, I completely failed to discover Quicken Online until today. I was blown away. It doesn't have the full featureset of desktop Quicken, but it's got all the stuff I care about, wrapped in a gorgeous, responsive UI. They even officially support my new favorite browser, Safari, and there's an awesome iPhone interface for when I'm not near a computer. Within five minutes of signing up I had imported all my accounts and was ready to go.
If you haven't taken a look at Quicken Online yet, I recommend checking it out.